Pfaff Coverlock 4772 Service Manual
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Pfaff Coverlock 4772 Service Manual

Pfaff Coverlock 4772 Service Manual

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coverlock
4772
Service manual
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. edition January 1999

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  • Page 1 coverlock 4772 Service manual . edition January 1999...

  • Page 2: Table Of Contents

    Notes on the sewing machine Specifications of the coverlock 4772 Adjustment gauge of the coverlock 4772 Dismantling the housing of the coverlock 4772 Requirements for adjusting the coverlock 4772 Needle bar height and needle penetration points 1. Setting the needle bar height 2.
  • Page 3 Setting the thread tensions 33. Setting the release eccentric 34. Setting the release path of the thread tensions 35. Setting the release plate 36. Setting the thread tensions 37. Setting the thread check spring 37a. Setting the thread guide on the front housing panel Repair instructions 38.

  • Page 4: Foreword

    Foreword This service and repair manual is designed to help you carry out all repairs on the machine quickly and correctly. Adjustments should only be made if the settings deviate from the requirements described here. When checking or adjusting a machine, always proceed in the order described here. For easy reference every workstep is marked with a dot.

  • Page 5: Notes On The Sewing Machine

    6. To avoid the risk of electric shock, do not open the machine. There are no parts inside the machine which can be repaired by the operator. This is solely the responsibility of our qualified service staff. 7. Only original PFAFF parts are to be used.

  • Page 6: Specifications Of The Coverlock 4772

    Specifications of the coverlock 4772 Number of needles and threads: 3 needles - 5, 4 or 3-thread 1 needle - 2-thread Needles: System EL*705, cat. no. 2002 Thickness Nm 90/14 Nm 80/12 Stitch width: 3-thread: left needle 6.7 mm right needle 4.5 mm 4-thread: 6.7 mm...

  • Page 7: Adjustment Gauge Of The Coverlock 4772

    Adjustment gauge of the coverlock 4772 Order number: 93-415 503-21/555 A = Needle bar height (10.3 mm) B = Presser foot height (4.5 mm) C = Clearance of upper overedge looper to right needle (4.7 - 5.0 mm) D = Clearance of lower overedge looper to right needle (3.9 mm) (Scale with 0.6 mm increment)

  • Page 8: Dismantling The Housing Of The Coverlock 4772

    Dismantling the housing of the coverlock 4772 G Remove the mains plug from the machine. G Remove the fastening screw 1 (figure 1). G Remove the presser foot holder completely. G Remove the needles. G Remove the detachable work support / free arm to the left (figure 2).
  • Page 9 G Unscrew (approx. 3 turns) and remove the fastening screw 4 using a 2 mm Allen key (figure 5). G Remove the differential setting knob to the right (figure 6). G Remove the small cover to the motor guard (figure 7). G Unscrew and remove the three fastening two screws 6 to the stand cover.
  • Page 10 G Turn the handwheel in the normal direction until the needle bar is at its highest position. G Move the looper cover as far as possible to the right and then pull it down. G Loosen the four fastening screws 8 of the front housing panel (figure 9). G Unscrew and remove the fastening screw 9 and remove the cover (figure 10).
  • Page 11 G Unscrew and remove the fastening screw 15 to the microswitch housing (figure 13). G Remove completely the microswitch housing upwards. G Unscrew and remove the four fastening screws 16 to the baseplate (figure 14). G Remove the machine housing carefully from the base plate.

  • Page 12: Requirements For Adjusting The Coverlock 4772

    Requirements for adjusting the coverlock 4772 Requirement 1: For the following eccentrics the first screw must be touching the surface of the main shaft in the normal direction (figure 1): Stroke eccentric 1 Drive eccentric 2 for the needle bar and blade drive When in the starting position, the first screw of the lifting eccentric 3 must be aligned with the surface of the main shaft in the normal direction.
  • Page 13 The drive eccentric 5 for the ellipsoidal movement of the two thread chainstitch looper must be set so that the two thread chainstitch looper 16 is in the middle of the needles “C” and “D” (fig. 2a). Thus the screws of the drive eccentric are to be loosened. The drive eccentric must be set in accordance with fig.
  • Page 14 Note: When the clamp cranks of the lower and upper looper lever are parallel to the main shaft, the distance from the eccentrics 4 and 6 and the eccentric belt must be 1.0 - 1.5 mm (figure 5). Both drive levers of the lower and upper overedge looper 12 and 13 must be positioned in a row along the center line of the main shaft (figure 6).

  • Page 15: Needle Bar Height And Needle Penetration Points

    Needle bar height and needle penetration points 1. Setting the needle bar height Requirement: The vertical clearance between the right overedge needle and the top edge of the needle plate must be 10.3 mm when the needle bar 1 is at its upper dead center (figure 1). Check: G Turn the handwheel in the normal direction until the needle bar 1 is at its upper dead center (u.d.c.).

  • Page 16: Setting The Needle Penetration Points

    2. Setting the needle penetration points Requirement: When the needles are located in the lower dead center, the needle penetration points 4 must be cente- red in the needle plate with a clearance of 1 mm to the front of the needle plate (figure 3). Check: G Turn the handwheel in the normal direction until the needle bar is at its lower dead center.

  • Page 17: Setting The Main Feed Dog In The Sewing Direction With Regard To The Needle Plate

    Feed system 3. Setting the main feed dog in the sewing direction with regard to the needle plate Requirement: When the stitch length is set to “4”, the main feed dog must be centered between the front and the back of the needle plate in the sewing direction (figure 4).

  • Page 19: Setting The Feed Dog Movement

    4. Setting the feed dog movement Method: When the rising needle leaves the fabric, the feed dog moves up above the needle plate. The raised feed dog pushes the fabric to the rear. After completing the feed movement the feed dog drops down below the needle plate surface and the needle penetrates the fabric.

  • Page 21: Setting The Stitch Length

    5. Setting the stitch length Requirement: When the stitch-length adjustment knob is set to “4” and the adjustment lever for the differential feed is set to “standard”, the machine must sew a stitch of 4 mm. Check: G Set the longest stitch with the stitch-length adjustment knob (figures 9 and 10). G Set the adjustment lever for the differential feed to “standard”.

  • Page 22: Setting The Stitch Length Adjustment Knob

    6. Setting the stitch-length adjustment knob Requirement: When the stitch-length adjustment knob is at “4”, the scale of the stand cover (figure 11) must also read “4”. Check: G Attach the stand cover. G Set the stitch-length adjustment knob to “4”. G Carry out a visual check.

  • Page 23: Setting The Differential Feed Dog

    7. Setting the differential feed dog Requirement: With the maximum gathering setting and the stitch length at “3”, the differential feed dog 11 must be 0.5 mm from the needle plate (figure 13). Check: G Set the stitch-length adjustment knob to “3”. G Push down the adjustment lever for the differential feed dog as far as it will go.

  • Page 24: Setting The Differential Feed-Dog Height

    8. Setting the differential feed-dog height Requirement: The main feed dog 13 and the differential feed dog 14 must be positioned at the same height. Check: G Set the maximum stitch length and the maximum differential stroke. GTurn the handwheel in the normal direction until the descending main feed dog is flush with the surface of the needle plate (figure 15).

  • Page 25: Setting The Presser Bar Height

    9. Setting the presser bar height Requirement: With the presser bar lever raised there must be a 4.5 mm gap between the needle plate and the bottom of the presser foot. Check: G Turn the handwheel in the normal direction until the needle bar is at its lowest point. G With the presser bar lever raised, slide the adjustment gauge under the presser foot as in figure 16.

  • Page 26: Setting The Presser Bar Eccentrics

    10. Setting the presser bar eccentrics Requirement: The locking spring 17 must lock into the fan eccentric 18 as in figure 18. The fan eccentric 19 must also rest on the housing (figure 19). No axial play should be apparent in the shaft. Check: G Remove the housing cover according to the adjustment and repair instructions.
  • Page 27 Notes:...

  • Page 28: Setting The Lower Overedge Looper

    Setting the lower overedge looper 11. Setting the height of the lower overedge looper Requirement: The vertical clearance between the looper point and the looper drive shaft must be 47.6 mm (figure 20). Check: G Remove the housing as described in the adjustment and repair instructions. G Remove the sewing foot, the needle plate and the feed dog.

  • Page 29: Setting The Timing Of The Lower Overedge Looper

    12. Setting the timing of the lower overedge looper Note: The timing of the lower overedge looper is set by turning the handwheel back and forth. This method guarantees a 100 % setting. This is very important for machines with double eccentric. A new needle system EL*705 Nm 90 must be used for all the following steps.

  • Page 31: Setting The Looper-To-Needle Clearance

    13. Setting the looper-to-needle clearance Requirement: When the looper point is in the scarf of the needle while moving to the right, the looper-to-needle clea- rance must be between 0 and 0.05 mm (figure 25). Check: G Turn the handwheel in the normal direction until the looper point is exactly in the scarf of the right needle while moving to the right.

  • Page 33: Setting The Lateral Clearance To The Right Needle

    14. Setting the lateral clearance to the right needle Requirement: When the needle bar has moved 4.1 mm upwards from its lowest position (lower dead center), the loo- per point 4 must be positioned as shown in figure 27. Check: G Move the needle bar to its lowest position by turning the handwheel.

  • Page 34: Setting The Upper Overedge Looper

    Setting the upper overedge looper 15. Setting the height of the overedge looper Requirement: When the upper overedge looper has reached its point of reversal, the distance between the hook point and the needle plate must be 10.5 mm. Check: G Turn the handwheel in the normal direction until the upper overedge looper is in the position seen in figure 29.

  • Page 35: Setting The Lateral Clearance To The Right Needle

    16. Adjusting the lateral clearance to the right needle Requirement: When the upper overedge looper is at its left point of reversal, the distance from the looper eye to the right needle must be 4.7 to 5.0 mm (figure 30). Check: G Turn the handwheel in the normal direction until the upper looper is at its left point of reversal.

  • Page 36: Setting The Timing Of The Upper Overedge Looper

    17. Setting the timing of the upper overedge looper Requirement: When the two loopers overlap as shown in figure 32 the clearance between the point of the upper looper 16 and the head of the lower looper 4 must be between 0.05 and 0.1 mm. Check: G Turn the handwheel in the normal direction until the upper looper 16, in its upward movement, is behind the lower looper 4.

  • Page 37: Setting The Clearance Between The Upper And Lower Overedge Looper

    18. Setting the clearance between the upper and lower overedge loopers Requirement: When the two loopers overlap (figure 33), the clearance between the point of the upper looper 16 and the back of the lower looper 4 must be between 0.05 and 0.1 mm. Check: G Turn the handwheel in the normal direction until the upper looper 16, in its upward movement, is behind the lower looper 4.

  • Page 38: Setting The Two Thread Chainstitch Looper

    Setting the two thread chainstitch looper 19. Setting the height of the two thread chainstitch looper Requirement: The vertical clearance between the looper point and the looper drive shaft must be 65.8 mm (figure 34) Check: G Turn the handwheel in the normal direction until the looper point 16 is at its right point of reversal. G The vertical clearance between the looper point and the looper drive shaft must be 65.8 mm in this position.

  • Page 39: Setting The Lateral Clearance To The Cover Stitch Needle (D)

    20. Setting the lateral clearance to the cover stitch needle (D) Requirement: When the two thread chainstitch looper is at its right point of reversal 16, the clearance of the looper eye to needle “D” should be 6.2 mm (fig. 35). When this clearance is set correctly, the clearance of the two thread chainstitch looper 16 to the needle is 2.5 mm (fig.

  • Page 40: Setting The Looper-To-Needle Clearance

    21. Setting the looper-to-needle clearance Requirement: The looper point must touch the scarf of the needle (D) while moving to the front (fig. 37). When at the rear there should be a clearance of 0.05 - 0.1 mm. Check: G Turn the handwheel in the normal direction until the looper point is exactly in the scarf of the needle (D) while moving to the left.

  • Page 41: Setting The Timing Of The Two Thread Chainstitch Looper

    22. Setting the timing of the two thread chainstitch looper Requirement: When the needle bar has moved 3.5 mm upwards from its lowest position, the point of the two thread chainstitch looper 16 must be at the middle of the needle (D) (figure 39). Check: G Turn the handwheel in the normal direction until the needle bar is in its lowest position.

  • Page 43: Setting The Needle Guards

    Setting the needle guards 23. Setting the rear needle guard Requirement: When the looper point of the lower overedge looper 4 is precisely in the center line of needle B and A when moving to the right, the needles should be positioned right next to the rear needle guard 20 (figure 42).

  • Page 44: Setting The Front Needle Guard

    24. Setting the front needle guard Requirement: When the looper point of the lower overedge looper 4 is precisely in the center line of the needle when moving to the right, then a clearance of between 0 and 0.05 mm must be apparent between the left and right needles and the front needle guard 23 (figure 43).

  • Page 45: Setting The Needle Guard For The Cover Stitch Needles

    25. Setting the needle guard for the cover stitch needles Requirement: When the needle bar is in its lowest position, there should be a clearance of 0 - 0.05 mm between the needles “C” for “D” and the front needle guard (fig. 45). Check: G Turn the handwheel in the normal direction, until the needle bar is in its lowest position.

  • Page 46: Setting The Upper And Lower Blades

    Setting the upper and lower blades 26. Setting the lower blade Requirement: The cutting edge of the lower blade must be flush with the top edge of the needle plate (figure 47). Check: G Carry out a visual check. Setting: G Loosen the screw 29.

  • Page 47: Setting The Upper Blade

    27. Adjusting the upper blade Requirement: With the upper blade at its lowest point, the upper and lower blades must overlap by 1.0 to 1.5 mm while at the same time forming a right angle to the needle plate (figure 48). Check: G Turn the handwheel in the normal direction until the upper blade is at its lowest point.

  • Page 48: Setting The Lower Blade Bracket

    28. Setting the lower blade bracket Requirement: Should the adjustment knob 37 for the seam width be positioned at the lowest or highest number, then the bracket 38 must be lined up with the increment lines (figure 51). The chaining finger 39 must be between 0 and 0.2 mm underneath the needle plate (figure 52). Check: G Turn the adjustment knob 37 as far as it will go.

  • Page 49: Setting The Chaining Finger

    29. Setting the chaining finger Requirement: If the adjustment knob 42 is set to “S”, the locking spring 43 of the chaining finger 44 must lock correctly into place (figure 53). The chaining finger 44 may only have a minimum of vertical play when set in this position. Check: G Remove the needle plate.

  • Page 50: Setting The Looper Thread Guides

    Setting the looper thread guides 30. Setting the looper thread guide of the lower overedge looper Requirement: The looper thread guide 48 must be at its standard setting as shown in figure 54. Setting: G Loosen the screw 49. G Adjust the looper thread guide 48 until it is touching the screw 2. G Tighten the screw 49.

  • Page 51: Setting The Looper Thread Guides Of The Two Thread Chainstitch Looper

    32. Setting the looper thread guides of the two thread chainstitch looper Requirement 1: When the upper overedge looper is at its lowest position, the large looper thread guide 52, in its standard setting, should have a clearance of approx. 0.5 mm to the raised part 53 of the base plate (figure 56).

  • Page 52: Setting The Thread Tensions

    Setting the thread tensions 33. Setting the release eccentric Note: Only the blue and green thread tensions are released when the presser bar lever is raised Requirement: When the presser bar lever is lowered, the release eccentric 58 and its groove 59 must face upward vertically (figure 57).

  • Page 53: Setting The Release Path Of The Thread Tensions

    34. Setting the release path of the thread tensions Requirement: When the presser bar is raised, the tension disc 62 must have a clearance of approx. 0.5 mm to the tension disc 63 (Figure 58). Check: G Remove the front housing in accordance with the adjustment and repair instructions. G Raise the presser bar lever.

  • Page 54: Setting The Release Plate

    35. Setting the release plate Note: This adjustment should only be carried out if a compelling reason exists. Requirement: Both tension release levers 69 and 70 should have a clearance of 1.5 mm to the blue and/or green thread tension barrels (figure 59). Setting: G Remove the front housing panel in accordance with the adjustment and repair instructions.

  • Page 55: Setting The Thread Tensions

    36. Setting the thread tensions Requirement: G The thread tensions on the machine are adjusted individually using adjustment dials (figure 61). GThe higher the number set on the dial, the higher the thread tension. 0 = lowest tension 9 = highest tension G The correct thread tension can only be attained when the machine is threaded correctly.

  • Page 56: Setting The Thread Check Spring

    37. Setting the thread check spring Requirement: When there is a weight of 10 grams on the thread check spring, there should be a clearance of 0.2 - 1.0 mm to the stop 77 (fig. 62). The thread check spring should be set in accordance with fig. 63. Setting: G Turn the adjusting screw 78, until the thread check spring is set correctly.

  • Page 57: Repair Instructions

    Repair instructions 38. Replacing the motor Disassembly: G Remove the housing as described in the adjustment and repair instructions. G Using a small screwdriver, remove the cover 1 to the handwheel (figure 1). G Unscrew the fastening screw 2 and remove the washer 3. G Remove the handwheel.

  • Page 59: Replacing The Microswitch

    39. Replacing the microswitch Disassembly: G Remove the housing cover as described in the adjustment and repair instructions. G Cut open cable clip 9 (figure 5). G Pull the insulation tube 10 to one side. G Pull out the plug-in connector of the microswitch cable. G Press both clips 11 of the housing cover 12 to one side and remove the microswitch cover 13 (figures 6 and 7).
  • Page 61 Notes:...

  • Page 62: Safety Test

    Safety test 40. Electrical safety test According to the German law on safe machine operation from the 24th June 1986, the VDE-regulations are regarded as the official rules in electronics and are the basis for the regulations for testing electrical safety of technical devices.

  • Page 63: Electrical Safety Test With Abb Metrawatt M5013

    41. Electrical safety test with ABB Metrawatt M 5013 I) Mains voltage test: Volt = V G For all following tests insert the plug of the ABB Metrawatt M 5013 in the grounded mains socket. G Set the switch for the measuring range at “250 V” (figure 1). If there is mains voltage present, the LCD display shows how much (230 V +/- 10%).

  • Page 66: Measures To Be Taken In The Case Of Inadmissible Test Readings

    42. Measures to be taken in the case of inadmissible test values If one of the 4 test functions is a failure, the ground mains socket is defective. Inform your landlord. If the current consumption deviates considerably from the indicated value, although the machine does not bind, the motor is defective and must be exchanged or repaired.
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  • Page 70 PFAFF Gritznerstraße 11 76227 Karlsruhe Fernruf (0721) 40010 Technische Änderungen vorbehalten Fernschreiber 7825638 Subject to alterations in design Drahtwort Pfaffwerk Sous toute réserve de modifications techniques Telefax (0721) 4001513 Salvo modificaciones técniche Druckerei Gablenz GmbH Con riserva di modifiche tecniche Stettiner Straße 17...

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